Method for manufacturing prismatic secondary battery

ABSTRACT

A first electrode body element and a second electrode body element including a positive electrode plate and a negative electrode plate are fabricated, a first positive electrode tab group of the first electrode body element and a second positive electrode tab group of the second electrode body element are connected to a lead portion of a positive electrode collector attached to a sealing plate, a first negative electrode tab group of the first electrode body element and a second negative electrode tab group of the second electrode body element are connected to a lead portion of a negative electrode collector attached to the sealing plate, and the first electrode body element and the second electrode body element are arranged together as one such that an electrode body is formed.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention application claims priority to Japanese PatentApplication No. 2015-213990 filed in the Japan Patent Office on Oct. 30,2015, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a method for manufacturing a prismaticsecondary battery.

2. Description of Related Art

Prismatic secondary batteries such as alkaline secondary batteries andnonaqueous electrolyte secondary batteries are used m power sources fordriving electric vehicles (EV), hybrid electric vehicles (HEV, PHEV),and the like.

In such prismatic secondary batteries, a battery case is formed by abottomed tubular prismatic outer package including an opening and aseating plate that seals the opening. The battery case accommodatestherein an electrode body including positive electrode plates, negativeelectrode plates, and separators, and an electrolyte. A positiveelectrode terminal and a negative electrode terminal are installed inthe sealing plate. The positive electrode terminal is electricallyconnected to the positive electrode plates through a positive electrodecollector, and the negative electrode terminal is electrically connectedto the negative electrode plates through a negative electrode collector.

The positive electrode plate includes a positive electrode core bodymade of metal and a positive electrode active material layer formed onthe surface of the positive electrode core body. A positive electrodecore body exposed portion, on which no positive electrode activematerial layer is formed, is formed in a portion of the positiveelectrode core body. Furthermore, the positive electrode collector isconnected to the positive electrode core body exposed portion.Furthermore, the negative electrode plate includes a negative electrodecore body made of metal and a negative electrode active material layerformed on the surface of the negative electrode core body. A negativeelectrode core body exposed portion, on which no negative electrodeactive material layer is formed, is formed in a portion of the negativeelectrode core body. Furthermore, the negative electrode collector isconnected to the negative electrode core body exposed portion.

For example, Japanese Published Unexamined Patent Application No.2009-032640 (Patent Document 1) proposes a prismatic secondary batteryusing a wounded electrode body including a wounded positive electrodecore body exposed portion at one end portion and a wound negativeelectrode core body exposed portion at the other end portion.Furthermore, Japanese Published Unexamined Patent Application No.2008-226625 (Patent Document 2) proposes a prismatic secondary batterythat uses an electrode body provided with a positive electrode core bodyexposed portion and a negative electrode core body exposed portion atone end portion.

BRIEF SUMMARY OF THE INVENTION

Development of on-vehicle secondary batteries, particularly, secondarybatteries used in EVs and PHEVs that have a higher energy density and alarger battery capacity are awaited. In the case of the prismaticsecondary battery disclosed in Patent Literature 1 described above,spaces such as left and right spaces in which the wound positiveelectrode core body exposed portion and the wound negative electrodecore body exposed portion are disposed and an upper space between thesealing plate and the wound electrode body are required in the batterycase. Such a requirement is a factor hindering the increase in energydensity of the second battery.

Conversely, as is the case of the prismatic, secondary battery disclosedin Patent Literature 2, when the electrode body provided with thepositive electrode core body exposed portion and the negative electrodecore body exposed portion at one end portion is used, it will he easierto obtain a prismatic secondary battery with a high energy density.However, even if the electrode body provided with the positive electrodecore body exposed portion and the negative electrode core body exposedportion at one end portion were to be used, with conventionalmanufacturing methods, in particular, with conventional methods ofassembling a collector portion, it would be difficult to manufacture aprismatic secondary battery with a further increased energy density.

An object of the present disclosure is to provide a prismatic secondarybattery that is high in energy density.

In an aspect of the present disclosure, a method for manufacturing aprismatic secondary battery, the prismatic, battery including anelectrode body that includes a positive electrode plate and a negativeelectrode plate, an outer package that includes an opening and thathouses the electrode body, a sealing plate that seals the opening, apositive electrode collector electrically connected to the positiveelectrode plate, and a negative electrode collector electricallyconnected to the negative electrode plate, includes attaching thepositive electrode collector and the negative electrode collector to thesealing plate, electrically connecting a first positive electrode tabportion and a second positive electrode tab portion to the positiveelectrode collector and electrically connecting a first negativeelectric tab portion and a second negative electrode tab portion to thenegative electrode collector after disposing, in a short direction ofthe sealing plate, a first electrode body element including, on a firstside of the sealing plate, the positive electrode plate including thefirst positive electrode tab portion and the negative electrode plateincluding the first negative electrode tab portion, and a secondelectrode body element including, on a second side of the sealing plate,the positive electrode plate including the second positive electrode tabportion and the negative electrode plate including the second negativeelectrode tab portion, and arranging the first electrode body elementand the second electrode body element together as one.

According to the method described above, since the volume of the spaceoccupied by the collector portion including tab portions and thecollectors can be extremely small, a prismatic secondary battery havinga higher energy density can be obtained easily.

Note that in the connecting process, the displacement of each of theelectrode body elements and the order in which the tab portions and thecollectors are connected to each other are not limited to a particulardisplacement nor to a particular order. In the connection process, thefirst positive electrode tab portion and the second positive electrodetab portion may be electrically connected to the positive electrodecollector, and the first negative electrode tab portion and the secondnegative electrode tab portion may be electrically connected to thenegative electrode collector after the first electrode body element andthe second electrode body element are each disposed at the correspondingone of the two ends of the sealing plate. Furthermore, in the connectingprocess, the first electrode body element may be disposed on one side ofthe sealing plate and the first positive electrode tab portion may beelectrically connected to the positive electrode collector, and afterthe first negative electrode tab portion is electrically connected tothe negative electrode collector, the second electrode body element maybe disposed on the other side of the sealing plate and the secondpositive electrode tab portion may be electrically connected to thepositive electrode collector, and the second negative electrode tabportion may be electrically connected to the negative electrodecollector.

Desirably, the positive electrode collector is disposed on the sealingplate with the positive electrode insulating member in between, and thenegative electrode collector is disposed on the sealing plate with thenegative electrode insulating member in between.

Desirably, the first electrode body element includes a plurality ofpositive electrode plates and a plurality of negative electrode plates,a plurality of first positive electrode tab portions are stacked and aplurality of first negative electrode tab portions are stacked, thesecond electrode body element includes a plurality of positive electrodeplates and a plurality of negative electrode plates, and a plurality ofsecond positive electrode tab portions are stacked and a plurality ofsecond negative electrode tab portions are stacked.

Desirably, in the arranging process, one side of the first electrodebody element and one side of the second electrode body element arebrought into contact with each other.

Desirably, in the arranging process, the first positive electrode tabportion, the second positive electrode tab portion, the first negativeelectrode tab portion, and the second negative electrode tab portion arebent.

Desirably, in the connecting process, an auxiliary conductive member isconnected to at least one of the first positive electrode tab portion,the second positive electrode tab portion, the first negative electrodetab portion, and the second negative electrode tab portion, and at leastone of the first positive electrode tab portion, the second positiveelectrode tab portion, the first negative electrode tab portion, and thesecond negative electrode tab portion is electrically connected to thepositive electrode collector or the negative electrode collector withthe auxiliary conductive member in between.

The present disclosure is capable of providing a prismatic secondarybattery that is high in energy density.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a prismatic secondary battery accordingto an exemplary embodiment.

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2.

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 2.

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 2.

FIGS. 7A and 7B are plan views of a positive electrode plate and anegative electrode plate according to the exemplary embodiment.

FIG. 8 is a plan view of an electrode body element according to theexemplary embodiment.

FIG. 9 is a cross-sectional view of a portion in the vicinity of acurrent breaking mechanism in a longitudinal direction of a sealingplate.

FIG. 10 is a cross-sectional view of a portion in the vicinity of thecurrent breaking mechanism in a short direction of the sealing plate.

FIG. 11 is a diagram of a battery internal surface side of a sealingplate to which the collectors have been attached.

FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11.

FIGS. 13A to 13C are diagrams of prismatic secondary batteries accordingto modifications, corresponding to FIG. 12.

FIG. 14 is a plan view of an auxiliary member.

FIG. 15 is a diagram of a prismatic secondary battery according to amodification, corresponding to FIG. 12.

FIGS. 16A and 16B are cross-sectional views of electrode body elementsused in the prismatic secondary batteries according to themodifications.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a configuration of a prismatic secondary battery 20according to an exemplary embodiment will be described. Note that thepresent disclosure is not limited to the following exemplary embodiment

As illustrated in FIGS. 1 to 6, the prismatic secondary battery 20includes a prismatic outer package 1 that has an opening, and a sealingplate 2 that seals the opening. The prismatic outer package 1 and thesealing plate 2 are desirably made of metal and, for example, may bemade of aluminum or an aluminum alloy. The prismatic outer package 1includes a bottom 1 a, a pair of large-area side walls 1 b, and a pairof small-area side walls 1 c. The prismatic outer package 1 is abottomed and tubular outer package having a rectangular shape andincludes the opening at a position facing the bottom 1 a. A stackedelectrode body 3 in which a plurality of positive electrode plates 4 anda plurality of negative electrode plates 5 are stacked with separatorsinterposed therebetween are accommodated in the prismatic outer package1 together with an electrolyte.

Each positive electrode plate 4 includes a positive electrode core bodymade of metal and a positive electrode active material layer 4 a thatinclude a positive electrode active material formed on the positiveelectrode core body. Each positive electrode plate 4 includes, at one ofits ends, a positive electrode core body exposed portion 4 b in whichthe positive electrode core body is exposed. Note that, desirably, analuminum foil or an aluminum alloy foil is used for the positiveelectrode core body. Each negative electrode plate 5 includes a negativeelectrode core body made of metal and a negative electrode activematerial layer 5 a that include a negative electrode active materialformed on the negative electrode core body. Each negative electrodeplate 5 includes, at one of its ends, a negative electrode core bodyexposed portion 5 b in which the negative electrode core body isexposed. Note that, desirably, a copper foil or a copper alloy foil isused for the negative electrode core body. In the prismatic secondarybattery 20, each positive electrode core body exposed portion 4 bconstitutes a positive electrode tab portion 4 c, and each negativeelectrode core body exposed portion 5 b constitutes a negative electrodetab portion 5 c.

At an end portion of the electrode body 3 on the sealing plate 2 side,positive electrode tab portions 4 c are disposed in a stacked state toconstitute positive electrode tab groups (4 x and 4 y) and the negativeelectrode tab portions 5 c are disposed in a stacked state to constitutenegative electrode tab groups (5 x and 5 y). The stacked positiveelectrode tab portions 4 c are connected to a lead portion 6 c of apositive electrode collector 6. Furthermore, a positive electrodeterminal 7 is electrically connected to the positive electrode collector6. The stacked negative electrode tab portions 5 c are connected to alead portion 8 c of a negative electrode collector 8. Furthermore, anegative electrode terminal 9 is electrically connected to the negativeelectrode collector 8. A pressure-sensitive current breaking mechanism40 is provided in the conductive path between the positive electrodeplates 4 and the positive electrode terminal 7. The current breakingmechanism 40 is activated when the pressure inside the battery becomesequivalent to or higher than a predetermined value, and the electriccurrent is cut off by cutting off the conductive path between thepositive electrode plates 4 and the positive electrode terminal 7. Notethat the pressure-sensitive current breaking mechanism 40 may beprovided in the conductive path between the negative electrode plates 5and the negative electrode terminal 9.

The positive electrode terminal 7 is attached to the sealing plate 2 inan electrically insulated state with respect to the sealing plate 2 withan inner side insulating member 10 and an outer side insulating member11. Furthermore, the negative electrode terminal 9 is attached to thesealing plate 2 in an electrically insulated state with respect to thesealing plate 2 with an inner side insulating member 12 and an outerside insulating member 13. The inner side insulating members 10 and 12and the outer side insulating members 11 and 13 are desirably made ofresin. A terminal through-hole 7 x is provided in the positive electrodeterminal 7, and the terminal through-hole 7 x is sealed with a terminalplug 7 y.

The electrode body 3 is accommodated inside the prismatic outer package1 while being covered by an insulation sheet 14. Desirably, theinsulation sheet 14 is a resin sheet folded in a box shape or abag-shaped resin sheet. The sealing plate 2 is joined to an opening edgeportion of the prismatic outer package 1 by, for example, laser welding.The sealing plate 2 includes an electrolyte injection hole 15, and theelectrolyte injection hole 15 is sealed with a sealing plug 16 afterinjection of the electrolyte. A gas discharge valve 17 is formed in thesealing plate 2. The gas discharge valve 17 is activated when thepressure inside the battery becomes equivalent to or higher than apredetermined value and is for discharging gas inside the battery to theoutside of the battery. Note that the pressure in which the gasdischarge valve 17 is activated is set higher than the pressure in whichthe current breaking mechanism 40 is activated.

A method for manufacturing the prismatic secondary battery 20 will bedescribed next, Fabrication of positive electrode plate

A positive electrode slurry containing lithium-nickel-cobalt-manganesecomposite oxide as a positive electrode active material, polyvinylidenefluoride (PVdF) as a binding agent, a carbon material as a conductivematerial, and N-methylpyrrolidone (NMP) is fabricated. The positiveelectrode slurry is coated on both surfaces of a rectangular aluminumfoil that is 15 μm thick and that serves as the positive electrode corebody. Subsequently, by drying the above, the N-methylpyrrolidone in thepositive electrode slurry is removed and the positive electrode activematerial layers are formed on the positive electrode core body.Subsequently, a compression process is performed to compress thepositive electrode active material layers to a predetermined thickness.The positive electrode plate obtained in the above manner is cut into apredetermined shape.

Fabrication of Negative Electrode Plate

A negative electrode slurry containing graphite as a negative electrodeactive material, styrene-butadiene rubber (SBR) as the binding agent,carboxymethyl cellulose (CMC) as a thickener, and water is fabricated.The negative electrode slurry is coated on both surfaces of arectangular copper foil that is 8 μm thick and that serves as thenegative electrode core body. Subsequently, by drying the above, thewater in the negative electrode slurry is removed and the negativeelectrode active material layers are formed on the negative electrodecore body. Subsequently, as compression process is performed to compressthe negative electrode active material layers to a predeterminedthickness. The negative electrode plate obtained in the above manner iscut into a predetermined shape.

FIG. 7A is a plan view of a positive electrode plate 4 after cutting,and FIG. 7B is a plan view of a negative electrode plate 5 aftercutting. The positive electrode plate 4 includes rectangular areas thatare positive electrode active material layers 4 a formed on bothsurfaces of the positive electrode core body, and the positive electrodecore body exposed portion 4 b serving as the positive electrode tabportion 4 c is formed on one side of the positive electrode plate 4. Thenegative electrode plate 5 includes rectangular areas that are negativeelectrode active material layers 5 a formed on both surfaces of thenegative electrode core body, and the negative electrode core bodyexposed portion 5 b serving as the negative electrode tab portion 5 c isformed on one side of the negative electrode plate 5. Note that the sizeof the positive electrode plate 4 is slightly smaller than the size ofthe negative electrode plate 5. Desirably, an insulating layer or aprotective layer 4 d that has an electric resistance that is higher thanthat of the positive electrode core body is provided at the base portionof the positive electrode tab portion 4 c. Note that conductive membersother than the above may be connected to the positive electrode corebody exposed portion 4 b or the negative electrode core body exposedportion 5 b to serve as the positive electrode tab portion 4 c or thenegative electrode tab portion 5 c. respectively.

Fabrication of Electrode Body Elements

Stacked electrode body elements (3 x and 3 y) are fabricated byfabricating 50 pieces of positive electrode plates 4 and 51 pieces ofnegative electrode plates 5 with the above methods and by stacking eachpositive electrode plate 4 and each negative electrode plate 5 on eachother with a rectangular polyolefin separator therebetween. Asillustrated in FIG. 8, the stacked electrode body elements (3 x and 3 y)are fabricated such that the positive electrode tab portions 4 c of thepositive electrode plates 4 and the negative electrode tab portions 5 c.of the negative electrode plates 5 are stacked at one end portion of theelectrode body 3. Separators may be disposed on both outer surfaces ofthe electrode body elements (3 x and 3 y) and the electrode plates andthe separators may be fixed with tapes 18 and the like in a stackedstate. Alternatively, an adhesion layer may be provided on eachseparator such that the separators and the positive electrode plates 4,and the separators and the negative electrode plates 5 are adhered toeach other. Note that the size of the separator in plan view is the sameor larger than the size of the negative electrode plate 5. Each positiveelectrode plate 4 may be disposed between two separators and after heatwelding the outer peripherals of the separators, each of the positiveelectrode plates 4 and each of the negative electrode plates 5 may bestacked on each other.

Attaching Positive Electrode Terminal and Current Breaking Mechanism toSealing Plate

FIG. 9 is a cross-sectional view of a portion in the vicinity of thecurrent breaking mechanism 40 in a longitudinal direction of the sealingplate 2. FIG. 10 is a cross-sectional view of a portion in the vicinityof the current breaking mechanism 40 in a short direction of the sealingplate 2.

A positive electrode terminal mounting hole 2 a serving as athrough-hole is formed in the sealing plate 2. The outer side insulatingmember 11 is disposed on the battery outer surface side of the positiveelectrode terminal mounting hole 2 a, and the inner side insulatingmember 10 and a conductive member 41 are disposed on the battery innersurface side. Furthermore, the positive electrode terminal 7 is insertedfrom the outer side of the battery through the through-holes formed inthe outer side insulating member 11, the sealing plate 2, the inner sideinsulating member 10, and the conductive member 41, and the tip of thepositive electrode terminal 7 is riveted on the conductive member 41.Note that the riveted portion of the tip of the positive electrodeterminal 7 is, desirably, further welded to the conductive member 41.

Desirably, the conductive member 41 has a cup-shape that includes anopening portion 41 x open towards the electrode body 3 side. Theconductive member 41 includes a base portion 41 a that is disposedparallel to the sealing plate 2, and a cylindrical portion 41 b thatextends from the base portion 41 a towards the electrode body 3 side.The cylindrical portion 41 b may have a cylindrical shape or may be arectangular tubular portion. The conductive member 41 is made of metaland, desirably, is made of aluminum or an aluminum. alloy. The positiveelectrode terminal 7 is connected to the base portion 41 a. Note thatthe positive electrode terminal 7 and the conductive member 41 may be anintegral component. In such a case, the positive electrode terminal 7 isinserted into the through-holes of the components from the inner side ofthe battery and is riveted on the outer side of the battery.

The timer side insulating member 10 includes an insulating member bodyportion 10 a disposed between the sealing plate 2 and the base portion41 a of the conductive member 41, a pair of insulating member first sidewalls 10 b that extend from the two end portions of the insulatingmember body portion 10 a in the short direction of the sealing plate 2towards the electrode body 3 side, and a pair of insulating membersecond side walls 10 c that extend from the two end portions of theinsulating member body portion 10 a in the longitudinal direction of thesealing plate 2 towards the electrode body 3 side. A protrusion 10 d isformed an the outer surface of each insulating member first side wall 10b.

Subsequently, a deformation plate 42 is disposed so as to close theopening portion 41 x of the conductive member 41 on the electrode body 3side, and the outer peripheral edge of the deformation plate 42 isjoined to the conductive member 41 by laser welding or the like. Withthe above, the opening portion 41 x of the conductive member 41 on theelectrode body 3 side is sealed in an airtight manner. The deformationplate 42 is made of metal and, desirably, is made of aluminum or analuminum alloy. The shape of the deformation plate 42 is desirably thesame as that of the opening portion 41 x of the conductive member 41. Inthe prismatic secondary battery 20, the deformation plate 42 has acircular shape in plan view.

Subsequently, a dielectric plate 43 is disposed on the surface of thedeformation plate 42 on the electrode body 3 side. The dielectric plate43 includes a dielectric plate body portion 43 a disposed between thedeformation plate 42 and a collector body portion 6 a of the positiveelectrode collector 6, and a pair of dielectric plate first side walls43 b that extend from two edge portions of the dielectric plate bodyportion 43 a in a short direction of the sealing plate 2 towards thesealing plate 2 side. A dielectric plate through-hole 43 c, a firstprojection 43 d 1, a second projection 43 d 2, a third projection 43 d3, and a fourth projection 43 d 4 are formed in the dielectric platebody portion 43 a. Furthermore, recesses 43 e are formed on the innersurface of the dielectric plate first side walls 43 b.

A projection 42 a formed in the middle portion of the deformation plate42 is inserted into the dielectric plate through-hole 43 c formed in thedielectric plate body portion 43 a. Furthermore, the inner surfaces ofthe dielectric plate first side walls 43 b are disposed so as to facethe outer surfaces of the insulating member first side walls 10 b.Furthermore, by fitting the protrusions 10 d and the recesses 43 e toeach other, the insulating member 10 and the dielectric plate 43 areconnected to each other. Note that the recesses 43 e may bethrough-holes.

Flange portions 41 c are provided on the end portions of the conductivemember 41 on the electrode body 3 side. Furthermore, hooking and fixingportions that can be hooked to the flange portions 41 c of theconductive member 41 are desirably provided on the surface of thedielectric plate body portion 43 a on the sealing plate 2 side. With theabove, the dielectric plate 43 is fixed to the conductive member 41.

Positive Electrode Collector

As illustrated in FIGS. 9 to 11, the positive electrode collector 6includes the collector body portion 6 a, the lead portion 6 c collector,and as collector connection 6 b that connects the collector body portion6 a and the lead portion 6 c o each other.

A through-hole 6 d for connection is formed in the collector bodyportion 6 a, and a thin wall portion 6 e is formed around thethrough-hole 6 d for connection. Furthermore, an annular groove portion6 f is provided inside the thin wall portion 6 e so as to surround thethrough-hole 6 d for connection. The thickness (the residual thickness)of the groove portion 6 f is smaller than that of the thin wall portion6 e. Note that the annual groove portion 6 f is a fragile portion and isbroken upon deformation of the deformation plate 42. In other words, thefragile portion is the portion to be broken. Note that since it is onlysufficient that the conductive path is cut off upon breakage of thefragile portion, both of the thin wall portion 6 e and the grooveportion 6 f do not have to be provided. Only the thin wall portion 6 eor only the groove portion 6 f may be provided. Alternatively, theconnection between the deformation plate 42 and the collector bodyportion 6 a may be a fragile portion without providing the thin wallportion 6 e of the groove portion 6 f. Alternatively, the fragileportion, such as the thin wall portion or a groove portion, may beprovided in the deformation plate 42. Note that the through-hole 6 d forconnection is not an essential configuration, and the thin wall portionprovided in the collector body portion 6 a may be connected to thedeformation plate 42.

A first through-hole 6 y 1 for fixing, a second through-hole 6 y 2 forfixing, a third through-bole 6 y 3 for fixing, and a fourth through-hole6 y 4 for fixing are provided in the collector body portion 6 a. Arecess is provided around each of the first through-hole 6 y 1 forfixing, the second through-hole 6 y 2 for fixing, the third through-hole6 y 3 for fixing. and the fourth through-hole 6 y 4 for fixing.

Attaching Positive Electrode Collector

The positive electrode collector 6 described above is disposed on thesurface of the dielectric plate 43 on the electrode body 3 side. In sodoing, the first projection 43 d 1, the second projection 43 d 2, thethird projection 43 d 3, and the fourth projection 43 d 4 formed in thedielectric plate 43 are respectively inserted into the firstthrough-hole 6 y 1 for fixing, the second through-hole 6 y 2 for fixing,the third through-hole 6 y 3 for fixing, and the fourth through-hole 6 y4 for fixing formed in the positive electrode collector 6. Subsequently,by expanding the diameters of the tips of the first projection 43 d 1,the second projection 43 d 2, the third projection 43 d 3, and thefourth projection 43 d 4, the positive electrode collector 6 is fixed tothe dielectric plate 43. With the above, a first fixed portion 70 a, asecond fixed portion 70 b, a third fixed portion 70 c, and a fourthfixed portion 70 d are formed. Note that the projections may bepress-fitted into the through-holes for fixing.

Gas is sent in through the terminal through-hole 7 x formed in thepositive electrode terminal 7 from the outer side of the battery, suchthat the deformation plate 42 is urged against the collector bodyportion 6 a of the positive electrode collector 6. In the above state,the edge portion of the through-hole 6 d for connection provided in thecollector body portion 6 a of the positive electrode collector 6 and thedeformation plate 42 are joined together by laser welding or the like.Note that the through-hole 6 d for connection is not an essentialconfiguration and a collector body portion 6 a that has no through-hole6 d for connection may be joined to the deformation plate 42. Theterminal through-hole 7 x is sealed with the terminal plug 7 y.

As illustrated in FIGS. 9 to 11, the collector body portion 6 a of thepositive electrode collector 6 is disposed on the surface of thedielectric plate 43 on the inner side of the battery. The collectorconnection 6 b that extend towards the sealing plate 2 the collectorbody portion 6 a is provided at an end portion of the collector bodyportion 6 a. Furthermore, the lead portion 6 c is provided so as toextend along the sealing plate 2 from an end portion of the collectorconnection 6 b on the sealing plate 2 side towards the gas dischargevalve 17. The lead portion 6 c is disposed parallel to the sealing plate2. The lead portion 6 c is disposed on the sealing plate 2 with a leadportion insulating member 19 (a positive electrode insulating member) inbetween. Note that the lead portion insulating member 19 may be formedwith the inner side insulating member 10 or the dielectric plate 43 inan integrated manner,

Attaching Negative Electrode Terminal to Sealing Plate

A negative electrode terminal mounting hole 2 b serving as athrough-hole is formed in the sealing plate 2. The outer side insulatingmember 13 is disposed on the outer surface side of the negativeelectrode terminal mounting hole 2 b, and the inner side insulatingmember 12 and a collector body portion 8 a of the negative electrodecollector 8 are disposed on the inner surface side. A through-hole 8 dis provided in the collector body portion 8 a. Furthermore, the negativeelectrode terminal 9 is inserted from the outer side of the batterythrough the through-holes formed in the outer side insulating member 13,the sealing plate 2, the inner side insulating member 12, and collectorbody portion 8 a of the negative electrode collector 8, and the tip ofthe negative electrode terminal 9 is riveted on the negative electrodecollector 8. Furthermore, the riveted portion of the negative electrodeterminal 9 is welded to the negative electrode collector 8. The innerside insulating member 12 serves as a negative electrode insulatingmember. Note that when the current breaking mechanism 40 is not providedon the positive electrode side, the positive electrode collector 6 andthe positive electrode terminal 7 may be attached to the sealing plate 2through a configuration similar to that on the negative electrode side.

Connecting Tab Portions and Collectors to Each Other

As illustrated in FIGS. 11 and 12, the first electrode body element 3 xis disposed on one side of the sealing plate 2 in the short direction(the up-down direction in FIG. 11 and the left-right direction in FIG.12) and the second electrode body element 3 y is disposed on the otherside. Subsequently, the first positive electrode tab group 4 x of thefirst electrode body element 3 x is disposed on the lead portion 6 c ofthe positive electrode collector 6, and the first negative electrode tabgroup 5 x of the first electrode body element 3 x is disposed on thelead portion 8 c of the negative electrode collector 8. Furthermore, thesecond positive electrode tab group 4 y of the second electrode bodyelement 3 y is disposed on the lead portion 6 c of the positiveelectrode collector 6, and the second negative electrode tab group 5 yof the second electrode body element 3 y is disposed on the lead portion8 c of the negative electrode collector 8. In so doing, in the firstelectrode body element 3 x, the positive electrode tab portions 4 cconstituting the first positive electrode tab group 4 x are bundled onan undersurface 3 x 2 side of the first electrode body element 3 x.Furthermore, the negative electrode tab portions 5 c constituting thefirst negative electrode tab group 5 x are bundled on an undersurface 3x 2 side of the first electrode body element 3 x. In a similar manner,in the second electrode body element 3 y, the positive electrode tabportions 4 c that constitute the second positive electrode group 4 y arebundled on an undersurface 3 y 2 side of the second electrode bodyelement, 3 y and the negative electrode tab portions 5 c that constitutethe second negative electrode tab groups 5 y are bundled on theundersurface 3 y 2 side of the second electrode body element 3 y.

Subsequently, a high energy ray such as a laser beam is projected fromabove to the first positive electrode tab group 4 x and the secondpositive electrode tab group 4 y disposed on the lead portion 6 c of thepositive electrode collector 6 to weld the first positive electrode tabgroup 4 x and the second positive electrode tab group 4 y to the leadportion 6 c. Furthermore, a high energy ray such as a laser beam isprojected from above to the first negative electrode tab group 5 x andthe second negative electrode tab group 5 y disposed on the lead portion8 c of the negative electrode collector 8 to weld the first negativeelectrode tab group 5 x and the second negative electrode tab group 5 yto the lead portion 8 c. With the above, welded portions 50 x, 50 y, 60x, and 60 v are formed.

Note that in each of the first electrode body element 3 x and the secondelectrode body element 3 y, it is desirable that the positive electrodetab portions 4 c are joined to each other by welding or the like andpreliminary joint portions 51 x and 51 y are formed in advance beforeconnecting the tab portions and the collectors to each other.Furthermore, in a similar manner, preliminary joint portions are formedin advance on the negative electrode side as well by joining thenegative electrode tab portions 5 c to each other. Note that it isdesirable that the preliminary joint portions 51 x and 51 y be providedat positions opposing the lead portion 6 c of the positive electrodecollector 6. By so doing, in a case in which the positive electrode tabportions 4 c are bent so as to arrange the positive electrode tabportions 4 c together, the preliminary joint portions can prevent thebending process from becoming hampered. In the positive electrode tabportions 4 c after the bending process, the preliminary joint portions51 x and 51 y are, desirably, provided in areas that enables thepreliminary joint portions 51 x and 51 y to be disposed parallel to thelead portion 6 c.

Fabrication of Electrode Body

The first positive electrode tab group 4 x, the second positiveelectrode tab group 4 y, the first negative electrode tab group 5 x, andthe second negative electrode tab group 5 y are bent such that the uppersurface 3 x 1 of the first electrode body element 3 x and the uppersurface 3 y 1 of the second electrode body element 3 y illustrated inFIG. 12 comes into contact with each other. With the above, the firstelectrode body element 3 x and the second electrode body element 3 y areformed into a single electrode body 3 illustrated in FIGS. 3 to 6.

Assembling Prismatic Secondary Battery

The electrode body 3 that is attached to the sealing plate 2 is coveredwith the insulation sheet 14 and is inserted into the prismatic outerpackage 1. Subsequently, the sealing plate 2 and the prismatic outerpackage 1 is joined together by laser welding or the like and theopening of the prismatic outer package 1 is sealed. After the above,nonaqueous electrolyte containing an electrolyte solvent and electrolytesalt is injected through the electrolyte injection hole 15 provided inthe sealing plate 2. Subsequently, the electrolyte injection hole 15 issealed with the sealing plug 16.

Method for Manufacturing Prismatic Secondary Battery

With the method described above, the space occupied by the collectorportion can be made small easily without the structure of the collectorportion, formed by the connection between the positive electrode tabportions 4 c and the positive electrode collector 6 and the connectionbetween the negative electrode tab portions 5 c and the negativeelectrode collector 8, becoming complex. Accordingly, a prismaticsecondary battery with high energy density can be manufactured with asimpler method.

Furthermore, since the positive electrode collector 6 or the negativeelectrode collector 8 do not have to be bent after the positiveelectrode tab portions 4 c are connected to the positive electrodecollector 6 or after the negative electrode tab portions 5 c areconnected to the negative electrode collector 8, the connection betweenthe positive electrode tab portion 4 c and the positive electrodecollector 6 or the connection between the negative electrode tab portion5 c and the negative electrode collector 8 can be prevented frombecoming damaged.

Description of modifications will be given below. Note that in themodifications, components that are the same as those of the prismaticsecondary battery 20 described above are denoted with the same referencenumerals as those of the prismatic secondary battery 20. Furthermore,portions that are not described in particular may each have the sameconfiguration as that of the prismatic secondary battery 20 describedabove.

First Modification

FIG. 13A is a diagram of a prismatic secondary battery according to afirst modification, corresponding to FIG. 12. As illustrated in FIG.13A, the first positive electrode tab group 4 x and the second positiveelectrode tab group 4 y can he connected to the lead portion 6 c of thepositive electrode collector 6 while in a state in which a metalauxiliary member 30 is disposed on the first positive electrode tabgroup 4 x and the second positive electrode tab group 4 y.

FIG. 14 is a plan view of the auxiliary member 30. Two slit portions 30b are formed in a body portion 30 a of the auxiliary member 30. The slitportions 30 b are disposed so as to extend in the longitudinal directionof the sealing plate 2. Bend portions 30 c are formed at two ends (thetwo ends in the short direction of the sealing plate 2) of the bodyportion 30 a. The bend portions 30 c are bent from the body portion 30 aso as to stand erect from the body portion 30 a.

Regarding the connecting procedure, first, the auxiliary member 30 andthe lead portion 6 c of the positive electrode collector 6 hold thefirst positive electrode tab group 4 x and the second positive electrodetab group 4 y in between. Subsequently, by projecting a high energy raysuch as a laser beam to the edge portions of the slits 30 b provided inthe auxiliary member 30, the auxiliary member 30, the first positiveelectrode tab group 4 x or the second positive electrode tab group 4 y,and the lead portion 6 c of the positive electrode collector 6 arewelded to each other. By providing bend portions 30 c in the auxiliarymember 30, metal spatter occurring during welding can be prevented fromscattering to the electrode body elements (3 x and 3 y) side anddamaging the electrode body elements (3 x and 3 y).

As illustrated in FIG. 13A, by forming two rows of separate weldedportions 50 x in the short direction of the sealing plate 2, the firstpositive electrode tab groups 4 x can be connected to the lead portion 6c of the positive electrode collector 6 in a further firm manner. Sameapplies to the welded portions 50 y.

Note that an auxiliary member may be used on the negative electrode sideas well in a similar manner to that on the positive electrode side.Desirably, the auxiliary member on the positive electrode side is madeof aluminum or an aluminum alloy. The auxiliary member on the negativeelectrode side is desirably made of copper or a copper alloy.

Second Modification

FIG. 13B is a diagram of a prismatic secondary battery according to asecond modification, corresponding to FIG. 12, The difference betweenthe first modification and the second modification is the form of theauxiliary member 30 and the way in which the positive electrode tabportions 4 c and the negative electrode tab portions 5 c are bundled. Asin the second modification, the auxiliary member 30 may be divided intotwo. In other words, one of the auxiliary member 30 is connected to thefirst positive electrode tab group 4 x and the other auxiliary member 30is connected to the second positive electrode tab group 4 y.Furthermore, as in the second modification. the positive electrode tabportions 4 c can be bundled at the middle portion of each of the firstelectrode body element 3 x and the second electrode body element 3 y inthe stacking direction of the electrode plates.

Third Modification

FIG. 13C is a diagram of a prismatic secondary battery according to athird modification, corresponding to FIG. 12. The difference between thefirst modification and the third modification is the form of theauxiliary member 30. As illustrated in the third modification, insteadof providing slits 30 b in the auxiliary member 30, thin wall portions30 d may be provided. Furthermore, a high energy ray such as a laserbeam may be projected to the thin wall portions 30 d such that theauxiliary member 30, the first positive electrode tab group 4 x or thesecond positive electrode tab group 4 y, and the lead portion 6 c of thepositive electrode collector 6 are welded to each other.

Fourth Modification

FIG. 15 is a diagram of a prismatic secondary battery according to afourth modification, corresponding to FIG. 12. As illustrated in FIG.15, the first positive electrode tab group 4 x, the second positiveelectrode tab group 4 y, the first negative electrode tab group 5 x, andthe second negative electrode tab group 5 y can each be connected to thecorresponding one of the positive electrode collector 6 and the negativeelectrode collector 8 while the electrode body elements (3 x and 3 y)are inclined with respect to the sealing plate 2. With such a method,the load applied to the positive electrode tab portions 4 c, thenegative electrode tab portions 5 c. the joint portion between thepositive electrode tab portions 4 c and the positive electrode collector6, and the connection between the negative electrode tab portions 5 cand the negative electrode collector 8 can be reduced when the positiveelectrode tab portions 4 c and the negative electrode tab portions 5 care bent to arrange the first electrode body element 3 x and the secondelectrode body element 3 y together into one. Accordingly, a prismaticsecondary battery that has a higher reliability can be obtained. Notethat an angle θ formed between the electrode body elements (3 x and 3 y)and the sealing plate 2 is preferably 5° to 70° and, more preferably, is5° to 60°.

Fifth Modification

In the first to third modifications, examples in which the auxiliarymember 30 and the positive electrode tab groups (4 x, 4 y) are welded tothe lead portion 6 c of the positive electrode collector 6 at the sametime has been given. However, an auxiliary conductive member may beconnected to the positive electrode tab groups (4 x and 4 y) or thenegative electrode tab groups (5 x and 5 y) in advance. Furthermore, theauxiliary conductive member joined to the positive electrode tab groups(4 x and 4 y) or the negative electrode tab groups (5 x and 5 y) may beconnected to a collector.

FIGS. 16A and 16B are figures related to a prismatic secondary batteryaccording to a fifth modification in which the auxiliary conductivemember is connected to the first positive electrode tab group 4 x of thefirst electrode body element 3 x. As illustrated in FIG. 16A, anauxiliary conductive member 300 may be connected to the first positiveelectrode tab group 4 x of the first electrode body element 3 x bywelding. Note that a welded portion 500 x is formed by the welding.Furthermore, subsequently, the auxiliary conductive member 300 isconnected to the lead portion 6 c of the positive electrode collector 6.Regarding the method of connecting the auxiliary conductive member 300to the lead portion 6 c of the positive electrode collector 6, two endportions of the auxiliary conductive member 300 may be laser welded tothe lead portion be of the positive electrode collector 6.

Furthermore, as illustrated in FIG. 16B, while two auxiliary conductivemembers 300 and 301 hold the first positive electrode tab group 4 x ofthe first electrode body element 3 x in between, the auxiliaryconductive members 300 and 301 can be connected to the first positiveelectrode tab group 4 x in advance. Note that a welded portion 500 y isformed in the first positive electrode tab group 4 x, the auxiliaryconductive member 300, and the auxiliary conductive member 301.Furthermore, subsequently, at least one of the auxiliary conductivemembers 300 and 301 is connected to the lead portion 6 c of the positiveelectrode collector 6. Note that the method for connecting the firstpositive electrode tab group 4 x and the auxiliary conductive members300 and 301, and the method for connecting at least one of the auxiliaryconductive members 300 and 301 to the lead portion 6 c of the positiveelectrode collector 6 are not limited to any method in particular andresistance welding, ultrasonic welding, laser welding, or the like maybe used. Furthermore, the first positive electrode tab group 4 x and theauxiliary conductive members 300 and 301 may be connected to each otherin advance by riveting or the like and, after that, at least one of theauxiliary conductive members 300 and 301 may be welded and joined to thelead portion 6 c of the positive electrode collector 6.

Others

It is only sufficient that the present invention is applied to eitherone of the positive electrode side or the negative electrode side.

The method of connecting the positive electrode tab portions and thepositive electrode collector to each other and the method of connectingthe negative electrode tab portions and the negative electrode collectorto each other are not limited to any method in particular and, forexample, resistance welding, welding through projection of, for example,a high energy ray such as laser ultrasonic welding, or ultrasonicwelding may be used. The high energy ray used may include a laser beam,an electron beam, and an ion beam.

The electrode body element is not limited to a stacked type. Abelt-shaped positive electrode plate and a belt-shaped negativeelectrode plate with a belt-shaped separator in between may be wound asthe electrode body element.

While detailed embodiments have been used to illustrate the presentinvention, to those skilled in the art, however, it will be apparentfrom the foregoing disclosure that various changes and modifications canbe made therein without departing from the spirit and scope of theinvention. Furthermore, the foregoing description of the embodimentsaccording to the present invention is provided for illustration only,and is not intended to limit the invention.

1. A method for manufacturing a prismatic secondary battery including anelectrode body that includes a positive electrode plate and a negativeelectrode plate, an outer package that includes an opening and thathouses the electrode body, a sealing plate that seals the opening, apositive electrode collector electrically connected to the positiveelectrode plate, and a negative electrode collector electricallyconnected to the negative electrode plate, the method comprising:attaching the positive electrode collector and the negative electrodecollector to the sealing plate; electrically connecting a first positiveelectrode tab portion and a second positive electrode tab portion to thepositive electrode collector and electrically connecting a firstnegative electric tab portion and a second negative electrode tabportion to the negative electrode collector after disposing, in a shortdirection of the sealing plate, a first electrode body elementincluding, on a first side of the sealing plate, the positive electrodeplate including the first positive electrode tab portion and thenegative electrode plate including the first negative electrode tabportion, and a second electrode body element including, on a second sideof the sealing plate, the positive electrode plate including the secondpositive electrode tab portion and the negative electrode plateincluding the second negative electrode tab portion; and arranging thefirst electrode body element and the second electrode body elementtogether as one.
 2. The method for manufacturing a prismatic secondarybattery according to claim 1, wherein the positive electrode collectoris disposed on the sealing plate with the positive electrode insulatingmember in between, and wherein the negative electrode collector isdisposed on the sealing plate with the negative electrode insulatingmember in between.
 3. The method for manufacturing a prismatic secondarybattery according to claim 1, wherein the first electrode body elementincludes a plurality of the positive electrode plates and a plurality ofthe negative electrode plates, wherein a plurality of the first positiveelectrode tab portions are stacked and a plurality of the first negativeelectrode to portions are stacked, wherein the second electrode bodyelement includes a plurality of the positive electrode plates and aplurality of the negative electrode plates, and wherein a plurality ofthe second positive electrode tab portions are stacked and a pluralityof the second negative electrode tab portions are stacked.
 4. The methodfor manufacturing a prismatic secondary battery according to claim I,wherein in the arranging, one side of the first electrode body elementand one side of the second electrode body element are brought intocontact with each other.
 5. The method for manufacturing a prismaticsecondary battery according to claim 1, wherein in the arranging, thefirst positive electrode tab portion, the second positive electrode tabportion, the first negative electrode tab portion, and the secondnegative electrode tab portion are bent.
 6. The method for manufacturinga prismatic secondary battery according to claim 1, wherein in theconnecting, an auxiliary conductive member is connected to at least oneof the first positive electrode tab portion, the second positiveelectrode tab portion. the first negative electrode tab portion, and thesecond negative electrode tab portion, and at least one of the firstpositive electrode tab portion, the second positive electrode tabportion, the first negative electrode tab portion, and the secondnegative electrode tab portion is electrically connected to the positiveelectrode collector or the negative electrode collector with theauxiliary conductive member in between.